Monday, January 19, 2015

Sony A7 Mark II Review


Sony A7 Mark II

These are interesting times for Sony. The corporation as a whole has seen better days, but the camera division has been arguably one of the most innovative competitors in the digital still camera field since the introduction of the A7-series of cameras, which started off life with much fanfare and interest at the end of 2013. What followed were two iterations, the ultra-high ISO A7s and the in-body stabilized A7 Mark II. The headline specs this time around are:

  • 5-Axis sensor-shift image stabilization
  • Improved autofocus speed and tracking
  • XAVC S video codec, 50Mbps
  • S-Log2 picture setting  à la Sony A7s
  • Redesigned front grip
  • Front command dial relocated,  à la Nikon

For most cameras, this would be enough to create a distinction in model iterations. However, it's important to note what hasn't changed:

  • 117-point phase-detection and 25 contrast detection AF points: This is the same as the A7. By comparison, the Sony 6000 uses 179 phase detection points.
  • RAW format unchanged (14bit data mapped to 11-bit file)
  • Same NP-FW50 battery. For reference, the A7 is rated at 340 shots under the CIPA testing standard
  • Rear control cluster unchanged

The benefits of the new features speak for themselves, but they also don't address all of the issues that serious photographers would have hoped for in a second iteration of the A7. Without even going further, its obvious that the A7 Mark II is a good camera, easily better than the A7. However, if we speak about the essence of the camera... the soul if you will...is it a case of the worst of Sony...technology for technology's sake... or does it represent the best of the company by being a technological high-water mark?


Build and Design


Even though the A7 Mark II is recognizably the A7's successor, a lot has changed. The camera is now beefier in all dimensions, has a new protruding front grip, re-positioned command dials and a new textured surface. The metallic surface treatment looks dull next to the glossy smooth surface of the older camera, but it does give the camera an understated but stately appearance. The texture also makes the camera easier to hold on to. This is also a substantially heavier camera, coming in at just under 600g with battery. For perspective, this is roughly 125g heavier than the original A7, but 80g less than the Leica M Type 240 which these cameras draw inspiration from.


For most people, the redesigned grip will be an improvement. The problem with the original A7 was not that the grip was uncomfortable, but that it required you to contort your index finger over the EV compensation dial to get to the shutter release button. The new grip shape is better but not perfect. The holding position is a bit more natural, but the position of the front command dial is still not perfect. On cameras like the Olympus E-M1 or most of the Nikon DSLR's, this dial arrangement is done better. It's because the front command dial isn't as prominent and is positioned a bit low relative to the where the index finger rests.

Another downside of the redesign is the quality of the front and rear command dials themselves. These are now recessed wheels like those found on Nikon's, but the tactile feel is terrible. The dials have the wrong amount of resistance  (slightly too much) and turn with a mushy feeling. In contrast, the old dials were aesthetically pleasing (semi-exposed and with polished tops) and had almost the perfect amount of "click" when you turned them. (Aside: if you are keeping track, the command dials used in the A7 are the same as the one used for the A6000.)

Left: A7    Right: A7 Mark II

Otherwise, when you flip to the back of the camera, the control layout is more or less unchanged. The positive of this is that all of the high end Sony cameras from the RX100M3 through to the A7s share a common user interface. The downside is that certain deficiencies, like a clear and simple way to set up the autofocus system, are being institutionalized in this common user interface scheme. Close to the top of all serious photographers who use the Sony A7 and A6000 cameras is the wish for a better way to select where the active AF point is; this hasn't changed on the A7 Mark II.




Image Stabilization


The defining feature of the A7 Mark II is the in-body image stabilization. Though this is no longer a technological novelty, the fact that it is offered on a compact camera with a full-frame sensor is noteworthy. Note that is is not the first stabilized full-frame senor; Sony already did that back with the A900. The system works automatically with Sony's native lenses, but you must manually input the focal length if you are adapting a third-party lens to the camera.


Unlike the sensor-shift system used on the Olympus cameras, Sony's implementation works in conjunction with FE-mount lenses with image-stabilization. The image stabilization of the Sony FE 70-200mm f/4.0 G OSS works well with the standard A7, but when you pair it with the A7 Mark II, the ability to hand-hold the lens is noticeably increased. If you have reasonably steady hands, you should be able to get at least 4 stops of real-world hand-holding advantage with this combination, which equates to a minimum shutter speed of 1/12s for non-moving subjects. This puts the A7 Mark II / FE 70-200mm f/4 combo on par with the excellent Fujifilm XF 50-140mm F2.8 R LM OIS WR; both offer the equivalent field of view for their respective systems and class leading hand-holding performance. Regardless of what type of lens that you use with the A7 Mark II, the in-body image stabilization works  transparently. The operation is silent and the transition from no-lock to focus-lock is quick and uneventful. It only allows for 3-axis stabilization with non-native lenses; not an issue with focal lengths under 100mm, but from the 20mm range an up, the limitations of a sensor-shift system come into play. If you adapt a non-native lens that's 200mm and greater, you won't get the same hand-holding advantage as you would with lens with a lens-shift system.




As a work of technology, Sony's system does not disappoint. However, the real-world benefit might not be as significant as it is hyped up to be. Though the FE-lens selection is limited, it is composed of either zooms with built-in image stabilization or primes. In other words, the A7 cameras for the most part aren't really starved for low-light performance. The in-body stabilization of the Mark II makes the zooms better, but they were already competent to begin with. If you are using primes with the aperture wide-open, low light generally isn't a dire issue as well. Certainly, the addition of in-body image stabilization will allow for generally lower ISO settings, but the real benefit is not so much that low noise shooting is improved but that you have more room to stop down in low light situations.

However, it is not possible to talk about in-body image stabilization without mentioning the Olympus E-M1, and to that end, the A7 Mark II system is very good but it still isn't as effective as the Olympus system. While the respective company engineers might be privy to the technical details, the very obvious reason why is the difference size of the sensor. If all other things are equal (and they never are), a full frame sensor is 3.84 times larger than the the equivalent Micro Four Thirds sensor, implying that it is also roughly the same amount heavier. This means that a sensor shift system has to exert more force to stabilize a full-frame chip... and what's more it has to apply that force over a greater distance to cover the larger area of the sensor. Simply put, the performance that you see with the E-M1 (probably) can't be scaled up to a larger sensor format without some performance penalty. This, however, is nitpicking, as the Sony sensor shift system on the A7 Mark II is competitive enough on its own terms.

Autofocus 


Like the A7, and unlike the a7R, the A7 Mark II has phase-detection elements. There is a modest improvement in autofocus performance, but it's nonetheless underwhelming relative to what it competes against in the upper-tier camera world. In still subject acquisition, neither the first nor second A7 is  as fast as the Olympus E-M1, nor does the A7 Mark II track lateral motion as dependably as on an upper-level DSLR. Conversely, the lower-tier A6000 is quite good at these thing, but part of that is because of the difference expectations foisted on crop and full frame cameras. 

To subjectively quantify the difference between the new camera and the old camera, it's that the on the A7 if you hadn't been told that it had phase detection capabilities, you might not notice that they are there. The faster speed and of the Mark II gives the  phase detection motion tracking more prominence, it gives you more of a "phase detection feeling." However, it should be remembered that the phase detection capability is limited to the central portion of the sensor. On Wide Area or Zone area modes with  AF-C tracing, the camera will follow a moving target in the same way that the A6000 does but the focus lock will lag behind the subject at higher velocities. Fore/aft distance tracking is smooth and predictable, but the camera is noticeably weaker with lateral tracking. This appears to be a function of the camera's ability to specifically recognize patterns; in some instances the the AF system appears to be over-eager to grab on to textures. The pattern recognition system is certainly sensitive to identifying scene elements, but it's not as specific as you would hope for with critical detail. In practical terms, the A7 Mark II isn't significantly faster than the A7 if you need to focus for critical detail, as you would still be using the spot-focus mode.

Image Quality


Shutter Shock


Mirrorless cameras require two closings of the shutter curtains to create an exposure. Because the sensor is "on" be default to drive the live view display, the first shutter closing is used to clear the sensor before the exposure proper; the second shutter closing ends the exposure cycle after the sensor has accumulated information taken during the exposure. The problem with this arrangement is that there is mechanical movement during an exposure if physical shutters are used; this can introduce vibrations into the camera body during the exposure. All mirrorless cameras suffer from this to some extent; the A7 was not particularly prone to it, but the a7R was notorious for it.

The default setting on the A7 Mark II (like the A7 and A6000) is with an electronic first shutter curtain; only the closing shutter is mechanical. This reduces some of the of noise, but more importantly, eliminating the mechanical action of the first shutter articulation means that there is no mechanical vibration to upset the camera during the exposure. The downside is that the electronic shutter is subject to the same pitfalls as is normally associated with video capture, the most pertinent one being the so-called "jello-shutter effect." Turning off the electronic shutter option turns the A7 Mark II (and practically any Sony mirrorless camera) into a noisy device. The following is an example of the shutter shock effect at 1/30s, 1/60s and 1/125s with the A7 and A7 Mark II with the electronic first curtain shutter feature turned off. (The effect is being magnified here by placing the cameras directly on a rigid glass surface.) Click for the 100% crop view.




In other words, not much has changed in terms of shutter shock. It's an issue between 1/60s and 1/125s and is something that you have to watch out for if you want the best results when shooting on a tripod.

Image Noise


The following is an ad hoc demonstration of the camera's JPEG output quality through the ISO range, as compared to the original A7. The settings were:

  • High ISO NR off
  • Electronic first shutter curtain on
  • JPEG output set at extra fine
  • Dynamic range optimizer off
  • Crops taken from the center of each image

Pay attention to the legibility of the soda bottles for detail retention (or lack thereof) as the ISO value rises, speckling in the broad colour patches for overall image noise, as well as the harshness of the reflections and shadows as dynamic range decreases. These samples are not directly comparable to similar samples found elsewhere in this blog because of variable ambient lighting conditions. Click on images for 100% crop view.

ISO 3200
ISO 6400
ISO 12800

Overall, there isn't much difference to see. There does appear to be some hardware-level upgrade to the 24mp sensor between the generations (and that you would also see in RAW), but you can bet that a portion of the noise performance improvement is also due to changes in the camera firmware. A similar situation occurred between the Nikon D610 and D750; the D750 looks cleaner above ISO 6400 due to a combination of firmware and hardware upgrades. There's not much meaningful difference, but the default A7 Mark II tone curve seems to be a tad bit brighter, and there is less chroma noise in the shadows.

The deeper issue with the A7 Mark II, and all Sony cameras is the way that the RAW files are produced. The sensor is collecting 14-bit data, but it is truncated into a compressed 11-bit form. This is a stumbling block for advanced users who are accustomed to using un-compressed 14-bit files on other systems, and even though he A7 Mark II produces some stunning images, there is a certain amount of clarity and crispness that isn't there when compared to the Nikon D750, which uses a related Sony-sourced sensor. For enthusiasts, the drawbacks will be minimal, but for those who have specific workflow needs for paid work, the Sony RAW format is at the very least, something that could be expanded upon

Adapting Third-Party Lenses


As a general rule of thumb, the advanced Sony mirrorless cameras (NEX-6, NEX-7, A6000, A7 and above) are good cameras for adapting third-party lenses to. Think of these cameras as the affordable equivalent of an interchangeable medium formal digital back. The best way to use non-native lenses is with the camera in Aperture-priority mode; the exposure metering will automatically adjust the shutter speed, but aperture information won't be recorded in the image file. You will have to rely on the focus-peaking function.

This is where the caveats come in. Focus peaking is not a perfect method for determining where the plane of focus is; it outlines the areas of highest contrast... which may fall obliquely to the true plane of focus. This is exacerbated by Sony's implementation of focus peaking when it is set to "high"... the camera will tend to highlight an area as being in focus when it isn't quite. This isn't a problem for most shooting situations, but if you want to shoot with the aperture wide open, it is best to use the magnified view to confirm that that the focus is exactly where you intend it to be. Of course, that is less of a concern if you are going to be mucking about with ultra-wide M lenses. Below is the Voigtlander Heliar Ultra Wide-Angle 12mm f/5.6; its pretty much the widest rectilinear wide-angle lens you can get for full frame, and at a price of under $750 USD, it isn't terribly expensive. Even though it has a proper focus ring, pretty much everything is in focus no matter what setting you put the ring at. (No, really, plug in the the values for 12mm, 3 feet and f/5.6 on a full frame system into a depth of field calculator and see what you get...)

With Voigtlander Heliar Ultra Wide-Angle 12mm f/5.6

Aside from the obvious difference in resolution, the difference between the a7R and the A7/Mark II sensors is in how the micro-lenses are offset. There is more of an offset on the a7R than on the A7, as that was the camera that Sony intended for M-mount users to gravitate to. (As an aside, I heard this as second hand with one who had spoken with somebody in chip fabrication. The misconception is that chips either have offset microlenses or they don't. The truth, apparently, is that all chips have some degree of offset, it's just that the a7R and Leica designs are more extreme in this regards.) The upshot is that with ultra wide lenses, the corners will tend to look sharper with less vignetting on the a7R. Is that a problem with the A7 Mark II? Well, mostly yes and partly no. Leica lenses aren't cheap and that is especially true of the good ones that are 24mm and wider. At the other end of the spectrum, none of the Voigtlander ultra-wide M mounts are truly "sharp"; if you are looking for technical perfection, this isn't it. However, the Heliar Ultra Wide-Angle 12mm f/5.6 is cheap and cheerful fun, providing good sharpness in middle of the lens; the corners.... well....um...
 
Un-retouched out of camera JPEG: Heliar 12mm f/5.6on Sony A7 Mark II

... let's just say that it's obviously not a landscape lens. To get the most out of this combination (and probably with any other non-native ultra-wide), you will have to expose to the right (ETTR) and edit in post processing as much as you can in order to get as much light as possible into the corners of the image. This is also a lens that doesn't particularly require image stabilization, as the minimal safe shutter speed is so low to begin with. However, where the in-body stabilizer helps is when you use this lens for video; the result again is not technically perfect, but it is visually striking.

Adapting Leica Lenses.


But of course, you weren't interested in adapting budget-friendly lenses with the in-body image stabilization, were you? To that end, the Leica Summilux-M 50mm f/1.4 ASPH mounted on the A7 Mark II:

With Leica Summilux-M 50mm f/1.4 ASPH

The results and potential results from this combination are astounding. With the longer 50mm focal length, corner-shading on the sensor photodiodes no longer becomes an issue. What you get is the crispness of the Leica lens, but with the tonality of the Sony sensor. This is actually good and bad on both fronts; the Summilux 50mm is very sharp in the center, but its overall output is more distinctive rather than perfect. (If you want "perfect", that would be the Leica APO-Summicron-M 50mm f/2.0 ASPH...) As for the file quality, the default output of the Sony (contrasty and saturated) will not appeal to shooters who are accustomed to the more neutral look of the M Type 240. Of course that can be changed to taste. 

Un-retouched out of camera JPEG; one Tiki-rific coffee mug. Note the Sony-like colour rendition combined  with the distinctive "swirly" bokeh pattern of the Summilux 50mm. The center is astoundingly crisp for an image shot at f/1.4


It should also be noted that is is a fairly weighty setup. The A7 Mark II is fairly dense for a mirrorless camera; the A7 is noticeably lighter. The 50mm Summilux is also quite large and heavy for a Leica lens. However, if you like having some weight in your hands for a steadier shot, the combined mass will be reassuring. So is a Leica lens on the A7 Mark II the ultimate M-mount alternative? The answer is... mostly yes but with some caveats. The stabilization system works best with short focal lengths, which fits the bill with all M-mount lenses. The practical level of stabilization is roughly three stops with the Leica 50mm, four if you have steady hands. In functional terms, yes, the A7 Mark II is a better Leica than the M Type 240, but even the lesser A7 could be argued to be the same in some regards. However, it's definitely not the same user experience. Though it is cliché, the simpleness of the M camera aesthetic is the drawing point of the system; when you combine the two you still feel as though you are working with a Sony camera more so than you are using a Leica lens.

Sensor Stack Issues


It is also worth noting that adapting Leica lenses onto a Sony body means that some loss of optical quality is inevitable. There is the usual issue of using adapters; there's some amount of mechanical tolerance that the additional interface introduces, but the issue is also goes down to the heart of using non-native lenses. This is because the thickness of the glass cover in front of the sensor chip is difference on the various camera systems. Leica has one of the thinness because the rear element of an M-mount lens is placed extremely close to the sensor. This means that the light rays exiting an M-mount lens at a highly oblique angle before entering the sensor stack. Conversely, the Sony E/FE-mount places the exit of the lens mount further ahead of the sensor, meaning that light rays exit the lens and enter the sensor stack at a less steep angle. When you use a Leica lens on a Sony body, the steep angle of the exiting light rays have to pass through the thicker Sony sensor stack. Simply put, the Leica lenses weren't designed to account this, and as of such, there will be some (maybe not a lot) of image degradation in the corners with ultra-wide lenses and with wide-open apertures. For an in-depth look into the issue, go here and here.



Concluding Thoughts




Even though it eventually proved to be (moderately) commercially successful, the original Sony A7 concept was very much a 1st generation product; great concept with with some ideas that needed to be refined and developed. The basic concept of a compact modern full frame camera is obvious to appreciate, but the execution was rough around the edges. As a viable photographic system, the original A7 was lacking in lenses and would have needed some ergonomic polish to meet the expectations of people shooting DSLR's. In many ways, the A7 seemed like it appealed more to people graduating through the ranks of mirrorless cameras rather than as a alternative to owning a DSLR.

To that end, the A7 Mark II is something of a 1.5-generation camera. The in-body image stabilizer is no small thing, but it doesn't address the basic issues (focus point control, battery life, RAW file integrity) that the most experienced users are looking for. The grip comfort is a step forward, but the tactile feel of the command dials is a step back. The autofocus is better but it still relies on Sony's clunky user interface. The more things change the more they stay the same: this camera typifies Sony in so many ways. It's a technological tour-de-force, it's a better camera but it still seems a bit overly gadget-y for its own good. However, despite the shortcomings, the A7 mark II most definitely is a better camera. In fact, it is more of a Leica M replacement than the a7R is. The a7R is a camera that many hoped for as a modern digital back for M-mount lenses, but the shutter-shock characteristics of that camera are an inconvenience to be aware of.

There are a lot of positives about the A7 Mark II, but even if a stabilized full frame sensor in a compact body is big news, this is still very much an evolutionary step. Conceivably, one day all future A7 variants will use the in-body image stabilization technology and we will take it for granted. Until then, the A7 Mark II is perhaps the most interesting platform to shoot with if you want the to shoot like you own a Leica without having to actually buy one.



With thanks to Broadway Camera


No comments:

Post a Comment